With advancing age, the visual acuity of a person decreases. A large proportion of persons over the age of 50 years of age require corrective lenses for both distance vision and near vision. They are equipped with bi-focals, tri-focals, or progressive lenses. A bi-focal lens has an upper distance vision correction combined with a lower near vision correction. A tri-focal lens, in addition to an upper distance vision correction and a lower near vision correction, has an intermediate vision correction. A progressive lens is a one piece multi-focal lens with a relatively smooth transition of correction from distance vision through to near vision.
In situations requiring distance vision correction, if the wearer is forced to look down through the lower near vision correction portion of the lens problems can be experienced. A person descending stairs does not have a clear view through the lower near vision correction portion of the lens. A person engaged in the game of golf does not have a clear view of the golf ball through the lower near vision correction portion of the lens. A person driving an automobile does not have a clear view of the speedometer through the lower near vision correction portion of the lens.
In view of these inherent difficulties, many persons prefer to wear ordinary distance lenses while engaged in activities where the bi-focal, tri-focal or progressive lenses interfere with the conduct and enjoyment of the activity. Unfortunately, the need for near vision correction still exists requiring such a person to carry on his or her person a near vision corrective lens for use as required. By way of example, when the golfer stops for lunch, near vision correction is required in order to read the menu. The person can either carry a second pair of glasses or can use a lens which is detachably secured to a front of a pair of eyeglasses in front of an eyeglass lens. An example of such a lens is U.S. Pat. No. 5,017,001 which issued to Kooketsu in 1991. Unfortunately, the Kooketsu lens is suitable for use as sunglasses, but is not particularly adapted for use as a near vision correction lens.